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Decay of Activity Complexes, Formation of Unipolar Magnetic Regions, and Coronal Holes in Their Causal Relation
Golubeva, E. M.; Mordvinov, A. V.
The peculiar development of solar activity in the current cycle resulted in an asynchronous reversal of the Sun's polar fields. The asymmetry is also observed in the formation of polar coronal holes. A stable coronal hole was first formed at the South Pole, despite the later polar-field reversal there. The aim of this study is to understand the pr…
Coronal magnetic field profiles from shock-CME standoff distances
Gopalswamy, N.; Cairns, Iver H.; Yashiro, S. +1 more
Coronagraphs observe coronal mass ejections (CMEs) and driven shocks in white light images. From these observations the shock's speed and the shock's standoff distance from the CME's leading edge can be derived. Using these quantities, theoretical relationships between the shock's Alfvénic Mach number MA and standoff distance, and empirical radial…
Investigating the Origin of Hot Gas Lines in Herbig Ae/Be Stars
Johns-Krull, Christopher M.; Cauley, P. Wilson
We analyze high-resolution UV spectra of a small sample of Herbig Ae/Be stars (HAEBESs) in order to explore the origin of the T ∼ 105 K gas in these stars. The C IV λ λ1548, 1550 line luminosities are compared to nonsimultaneous accretion rate estimates for the objects showing C IV emission. We show that the correlation between L C…
CO2 pressure broadening and shift coefficients for the 2-0 band of 12C16O
Vandaele, A. C.; Vander Auwera, J.; Hashemi, R. +3 more
Fourier transform absorption spectra of the 2-0 band of 12C16O mixed with CO2 have been recorded at total pressures from 156 to 1212 hPa and at 4 different temperatures between 240 K and 283 K. CO2 pressure-induced line broadening and line shift coefficients, and the temperature dependence of the former …
The Gini Coefficient as a Morphological Measurement of Strongly Lensed Galaxies in the Image Plane
Florian, Michael K.; Gladders, Michael D.; Li, Nan
Characterization of the morphology of strongly lensed galaxies is challenging because images of such galaxies are typically highly distorted. Lens modeling and source plane reconstruction is one approach that can provide reasonably undistorted images from which morphological measurements can be made, though at the expense of a highly spatially var…
A 17 June 2011 polar jet and its presence in the background solar wind
Jackson, B. V.; Buffington, A.; Hick, P. P. +3 more
High-speed jet responses in the polar solar wind are enigmatic. Here we measure a jet response that emanates from the southern polar coronal hole on 17 June 2011 at the extreme speed of over 1200 km/s. This response was recorded from the Sun-Earth line in Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) and Large Angle and Spectro…
The Time-evolution of HH 2 from Four Epochs of HST Images
Velázquez, P. F.; Bally, J.; Raga, A. C. +2 more
We have analyzed four epochs of Hα and [S II] Hubble Space Telescope images of the HH 1/2 outflow (covering a time interval from 1994 to 2014) to determine proper motions and emission line fluxes of the knots of HH 2. We find that our new proper motions agree surprisingly well with the motions measured by Herbig & Jones, although there is part…
High-resolution HI and CO observations of high-latitude intermediate-velocity clouds
Kerp, J.; Winkel, B.; Ben Bekhti, N. +1 more
Context. Intermediate-velocity clouds (IVCs) are HI halo clouds that are likely related to a Galactic fountain process. In-falling IVCs are candidates for the re-accretion of matter onto the Milky Way.
Aims: We study the evolution of IVCs at the disk-halo interface, focussing on the transition from atomic to molecular IVCs. We compare an atom…
The Goodness of Simultaneous Fits in ISIS
Rothschild, Richard E.; Fürst, Felix; Klochkov, Dmitry +15 more
In a previous work, we introduced a tool for analyzing multiple datasets simultaneously, which has been implemented into ISIS. This tool was used to fit many spectra of X-ray binaries. However, the large number of degrees of freedom and individual datasets raise an issue about a good measure for a simultaneous fit quality. We present three ways to…
An Observational Study of the Recurring Formation and Dissipation of a Dynamic Filament
Wang, Jingxiu; Zhang, Jie; Zhou, Guiping
Based on observations at the Hα wavelength from the Hinode spacecraft, we report here the detailed process of a dynamical filament that showed repeated appearance and dissipation in a filament channel. First, Hα short fibrils spreading in the pre-formed filament channel joined into longer threads. The joining process was found to be accompanied by…